The present invention relates to a tire and suspension warning and monitoring system that is composed of a set of sensors. These sensors monitor and measure current tire and suspension performance and periodically warn the driver when the tires or the suspension system needs servicing. There is one sensor for each tire on the vehicle. Each sensor measures the following tire and suspension performance (a) tire imbalance of each tire of a vehicle, (b) tire tread wear of each tire of a vehicle, and (c) shock absorber performance for each tire of a vehicle.
The handling performance of a motor vehicle, e.g., vehicle steering and braking, as well as fuel consumption, is affected by the condition of the tires and the suspension. Handling performance can be affected by improper tire inflation, abnormal tire tread wear, out of balance conditions, as well as by poorly performing shock absorbers.
It is estimated that ten percent of tires that would normally wear out at 40,000 miles actually wear out at 30,000 miles due to abnormal tire tread wear. As a result, over the course of vehicle life of 120,000 miles, the vehicle would need an additional set of tires, at an average cost of $300. Thus, it is desirable to alert the driver of abnormal tire imbalance.
A tire monitoring system currently available from SmarTire Systems, Inc. uses wireless technology to monitor the air pressure and temperature in vehicle tires using wireless wheel-mounted sensors and a display receiver mounted within sight and reach of the driver. One sensor is mounted on each wheel and the tire mounted over the sensor, each sensor containing a pressure transducer, a temperature transducer, a centrifugal switch, a radio transmitter and a lithium battery. The display module shows required pressure, actual pressure, pressure status and temperature. While this system provides temperature and pressure information, it does not provide information about tread wear, balance and shock absorber performance.
In addition, anti-lock braking systems (ABS) and integrated vehicle controllers (IVC) require the input of information indicating the wheel rotational speed for each wheel. Currently, a separate wheel speed sensor is provided for each wheel. It typically consists of a toothed wheel made of a magnetic disk attached co-axially to a corresponding axle rotatably supporting a tire and a pick-up coil arranged adjacent each toothed wheel with an interval therebetween to provide an alternating sensor signal having a frequency indicative of speed of each tire. It would be desirable to eliminate the need for this type of sensor by using a sensor, which also provides additional functions.
Co-pending U.S. patent application Ser. No. 09/454,443, discloses a system and method for monitoring vehicle conditions affecting tires including tire tread wear, shock absorber performance, balance condition of the vehicle tire, and rotational speed of a vehicle wheel.
While the above-noted co-pending application includes many features in common with those of the present invention, it does not include salient features of the present invention including informing a driver of the vehicle when various vehicle components will fail and informing the driver as to how much time until a component failure.